Cellular Respiration

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Cellular Respiration

• Cellular respiration is the process by which the
  chemical energy of "food" is converted into ATP.
• Carbohydrates, fats, and proteins can all be used
  as fuel for cellular respiration, but for our
  purposes we will look at how glucose is used.

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Cellular Respiration

• In the presence of oxygen, one gram of glucose
  releases 3811 calories of heat energy.
• However, if you were to read a nutrition label it
  would claim that one gram of glucose only
  releases 3.8 Calories.
• What is the difference between a calorie and
  Calorie?
• A food calorie, or Calorie, is actually equal to
  1000 calories, or 1 kcal. One calorie is the
  energy it takes to heat 1 g of water by 1 C.
  Therefore one Calorie, or food calorie, is just
  1000 times that, or the energy to heat 1 kg of
  water by 1 C.

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Overview of Respiration

• Respiration, like photosynthesis, is a multi-step
  process.
• The first step is a process called glycolysis.

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Glycolysis

• In glycolysis glucose is broken down into two
  molecules of pyruvate.
• This change is accompanied by a net gain of 2 ATP
  molecules and 2 NADH molecules.

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Glycolysis

• Notice from the picture that glycolysis requires
  some energy input.

2 ATP go in and 4 ATP come out for a net gain of
2 ATP.
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Glycolysis

• Also notice that glycolysis produces a molecule
  called NADH.
• NAD NADH
• This is very similar to the electron carrier we
  saw in photosynthesis.
• NADP NADPH
• If you are worried about getting the two confused
  just think NADPH has a P and is in
  Photosynthesis.

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Glycolysis

• Glycolysis occurs in ALL organisms.
• Glycolysis occurs in the cytoplasm of cells.
• It is always the FIRST step in converting the
  energy in food into ATP.
• Lets check it out!

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Following Glycolysis
Glucose
Glycolysis
2 Pyruvate, 2 ATP 2 NADH
In the presence of Oxygen
In the absence of Oxygen
Fermentation
Kreb Cycle Electron Transport Chain
Anaerobic Respiration
Aerobic Respiration
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Anaerobic Respiration

• Following glycolysis if oxygen is not present,
  pyruvate is metabolized in a process called
  fermentation.
• Fermentation complements glycolysis by recycling
  NADH back into NAD
• This allows glycolysis to continue and ATP to be
  produced.

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Fermentation

• Notice the recycling of NAD for glycolysis

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Fermentation

• There are two types of fermentation
• Lactic Acid Fermentation
• Lactic Acid is formed during fermentation.
• This occurs in our muscles.
• Alcoholic Fermentation
• Alcohol (and CO2) is formed during fermentation.
• This occurs in bacteria.

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Fermentation

• Fermentation can be performed by all organisms.
• It occurs following glycolysis in the absence of
  Oxygen.
• Fermentation occurs in the cytoplasm of cells.

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Summary of Anaerobic Respiration
The purpose of respiration is to convert the
energy in food into ATP. How much ATP does
anaerobic respiration create?
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Following Glycolysis
Glucose
Glycolysis
2 Pyruvate, 2 ATP 2 NADH
In the presence of Oxygen
In the absence of Oxygen
Fermentation
Kreb Cycle Electron Transport Chain
Anaerobic Respiration
Aerobic Respiration
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Aerobic Respiration

• Following glycolysis if oxygen is present,
  pyruvate is metabolized in two processes called
• The Kreb Cycle
• Electron Transport Chain
• The equation for aerobic respiration is

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From Glycolysis to the Kreb Cycle

• Following glycolysis, pyruvate is transported
  into the mitochondria.
• As it moves it loses carbon dioxide to form
  acetyl-CoA, a 2-carbon molecule.
• This process creates NADH.

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Kreb Cycle

• The Krebs cycle occurs in the mitochondrial
  matrix. It turns Acetyl-CoA into CO2. In doing
  so it generates a pool of chemical energy (ATP,
  NADH, and FADH2).
• Click picture to follow the link

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Electron Transport Chain
Click on the picture to see it in action
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Electron Transport Chain (ETC)

• The electron transport chain (ETC) consists of a
  series of molecules, mostly proteins, embedded in
  the inner mitochondrial membrane.
• The electron transport chain captures the
  electrons stored in NADH and FADH2 and passes
  them along the membrane.
• As the electrons move along the membrane H build
  up in the intermembrane space.
• The electrons are eventually passed to Oxygen.
  This makes Oxygen very negative. It quickly
  bonds with H to form water.
• The H that has built up in the intermembrane
  space wants out! It flows through a molecule
  called ATP synthase. As it does ATP is formed.
• Each NADH that donates electrons to the chain
  will fuel the creation of 3 ATP.
• Each FADH2 that donates elections to the chain
  will fuel the creation of 2 ATP.

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Aerobic Respiration
Glucose Carbon Dioxide During glycolysis, the
formation of Acetyl- CoA the Kreb
Cycle Oxygen Water During the electron
transport chain
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Aerobic Respiration

• Aerobic Respiration has three distinct parts
• Glycolysis occurs in the cytoplasm (yields 2 ATP)
• Krebs cycle takes place in the matrix of the
  mitochondria (yields 2 ATP)
• Electron transport chain is carried out on the
  inner mitochondrial membrane (yields 34 ATP)
• Total ATP 38!!!!

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SUMMARY
Glycolysis
Anaerobic Respiration
Aerobic Respiration
2 ATP
38 ATP